The invention relates to an apparatus for object scanning, in particular, an ultrasonic-scanning apparatus, comprising an articulated support for at least one scan head, particularly an ultrasonic head, and comprising an installation with angle indicators associated with the joints of the articulated support for the purpose of detecting point and/or directional coordinates of the scanning, given a random space positioning of the scan head, in dependence upon angular signals of the angle indicators.
To be included in the category of apparatus of this type are all those which permit, in any form, scannings of examination objects with the aim e.g. of determining the object outline, detecting object sectional planes, ascertaining direction or distance, respectively, of objects or the like in which a bearing is to be taken. All these forms of scanning basically amount to the detection of point and/or directional coordinates of the respective scanning. The scanning can proceed directly by means of a mechanical scan head on the object. However, it can also proceed by means of scanning media, such as light (e.g. laser), thermal radiation, sound, or the like. Of particular interest is scanning by means of ultrasound, whereby the apparatus for object scanning is then an ultrasonic scanning apparatus, and the scan head is an ultrasonic head.
Particularly with regard to ultrasonic scanning, ultrasonic sectional image apparatus are known which, for the detection of point coordinates and/or directional coordinates of the ultrasonic scanning, employ either the angular measurement relative to a horizontal or a vertical line, or the angular measurement between the successive elements of the articulated support (included angle, or complement of this angle, respectively).
The angular measurement relative to a horizontal or a vertical line (e.g. according to U.S. Pat. No. 3,924,452) indeed permits, on account of the simple coordinate relations, the utilization of angle indicators directly for the angle or such for the sine or cosine, respectively, of the angle (sine-cosine-potentiometers as angle indicators); however, the change in the angles must be mechanically transmitted at a fixed reference point; for example, by means of a cable or by means of a pantograph system similar to that of a drafting machine. The mechanical system must be highly precise and interference-insensitive with regard to temperature influences or also slippage. These conditions, of course, increase the cost of the entire system.
Up to the present time, the measurement of angles between the successive pivotally connected support elements is successful, in an analog fashion, only with a series-connection of potentiometers; or, in a digital fashion, with incremental angle indicators. However, a series-connection of potentiometers requires much space; moreover, it is expensive and very temperature-sensitive. Digital angle gauges are likewise high in cost-outlay, as well as temperature- and interference-sensitive. In addition, they require as a precondition the application of a computer (e.g. according to the article "A Computer-Controlled Ultrasound Image-Forming System" of S. Schorum, H. Fidel, from Searle Ultrasound, Santa Clara, Calif.).